authenticate.inc.php

<?php
if (!file_exists($userlist) || !is_readable($userlist)){
    $error = 'Login facility unavailable. Please try later.';
}
else{
    //read the file into an array called $users
    $users = file($userlist);
    //loop through the array to process each line
    for ($i = 0; $i < count($users); $i++){
        //separate each element and store in a temporary array
        $tmp = explode(', ', $users[$i]);
        //check for a matching record
        if ($tmp[0] == $username && rtrim($tmp[1]) == $password){
            $_SESSION['authenticated'] = 'Jethro Tull';
            session_regenerate_id();
            break;
        }
    }
    //if the session variable has been set, redirect
    if (isset($_SESSION['authenticated'])){
        header("Location: $redirect");
        exit;
    }
    else {
        $error = 'Invalid username or password.';
    }
}